A fuel injection system including a fuel rail and a fuel injector is described in European Patent No. EP 2 375 052 A1. A coupling device is provided, which includes a cup designed in such a way that it is hydraulically coupled to the fuel rail and forms a connection to a fuel inlet portion of the fuel injector. The cup has two boreholes through which screws extend. The ends of the screws are screwed into a plate, which engages at the fuel injector via a ring. The fuel injector is moreover held via a further ring so that a movement of the fuel injector in the two directions along a longitudinal axis is blocked. This known embodiment has the disadvantage that no pretensioning force is transmitted to the fuel injector.
Furthermore, an embodiment in which the fuel injector is sealed via a metallic ball/cone seal with respect to the fuel injector is conceivable. When the fuel injector is pulled against the rail via two screws with such a seal, this results in the problem that flexural stresses, which arise when the screws are unevenly tightened, are introduced into the fuel injector. To avoid this problem, pivoting motions between the fuel inlet portion of the fuel injector and the cup are possible via the ball/cone seal. This, however, then results in the problem that the size increases considerably, in particular along the longitudinal axis. With respect to the space constraints generally found, in particular inside an engine compartment of a motor vehicle or the like, this considerably limits the use of such possible approaches.